Sulfonates are a class of chemicals used in household, industrial, and institutional cleaning applications, personal care and agricultural products, metalworking fluids, industrial processes, emulsifying agents, corrosion inhibitors and as additives in lubricating oils. Some of the desirable properties of sulfonates for use in lubricating oil applications include their low cost, compatibility, water tolerance, corrosion inhibition, emulsion performance, friction properties, high temperature stability, rust performance, and light color.
Sulfonates that are used in lubricating oil applications have been classified as either neutral sulfonates, low overbased (LOB) sulfonates, or high overbased (HOB) sulfonates.
In the past, natural sulfonates, made as a by-product of white oil and process oil production, dominated the sulfonate market. However, as refineries switched to hydrotreating processes, which gave improved yields of process oils and white oils, and as the desire for higher utilization of raw materials and thus improved economics grew, synthetic sulfonates have become more readily available. Many synthetic sulfonates have been produced from sulfonated polyalkyl aromatic compounds. Unfortunately, many synthetic sulfonates provide properties that are inferior to the properties of the natural sulfonates. Thus, there is a need for low cost synthetic sulfonates that have good performance properties and can serve as a replacement for the natural sulfonates.
The present invention provides a polyalkenyl sulfonic acid composition comprising a mixture of polyalkenyl sulfonic acids derived from a mixture of polyalkenes comprising greater than 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers. The present invention also provides such a composition wherein the alkyl vinylidene isomer is a methyl vinylidene isomer, and the 1,1-dialkyl isomer is a 1,1-dimethyl isomer. Also provided is such a composition wherein the number average molecular weight of the polyalkene is about 168 to about 5000. In a preferred embodiment, the polyalkene is polyisobutene. In another preferred embodiment, the polyalkene is polyisobutene and the molecular weight distribution of the polyisobutenyl sulfonic acids has at least 80% of the polyisobutenyl sulfonic acids molecular weights separated by even multiples of 56 daltons. The present invention further provides such a composition wherein the polyalkene is polyisobutene and less than 20% of the polyisobutenyl sulfonic acids in the molecular weight distribution of the polyisobutenyl sulfonic acids contain a total number of carbon atoms that is not evenly divisible by four.
Also provided by the present invention is an improved method of making polyalkenyl sulfonic acid by sulfonating polyalkenes, wherein the improvement comprises using as the polyalkenes a mixture of polyalkenes comprising greater than 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers. The present invention further provides the product of this process.
The present invention further provides a polyalkenyl sulfonate composition having a TBN of about 0 to about 60 wherein the polyalkenyl sulfonate is an alkali metal or alkaline earth metal salt of a polyalkenyl sulfonic acid derived from a mixture of polyalkenes comprising greater than 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers. Further provided in accordance with this invention is a polyalkenyl sulfonate composition having a TBN of greater than 60 to about 400 wherein the polyalkenyl sulfonate is an alkali metal or alkaline earth metal salt of a polyalkenyl sulfonic acid derived from a mixture of polyalkenes comprising greater than 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers.
In accordance with the present invention there is also provided an improved method of making polyalkenyl sulfonate by sulfonating polyalkenes and reacting the resulting polyalkenyl sulfonic acid with an alkali metal or alkaline earth metal, the improvement comprising using as the polyalkenes a mixture of polyalkenes comprising greater than 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers. The present invention also provides the product produced by this process.
Also provided by the present invention is a lubricating oil composition comprising a major amount of an oil of lubricating viscosity and a minor amount of a polyalkenyl sulfonate composition having a TBN of about 0 to about 60 wherein the polyalkenyl sulfonate is an alkali metal or alkaline earth metal salt of a polyalkenyl sulfonic acid derived from a mixture of polyalkenes comprising greater than 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers. The present invention also provides a lubricating oil composition comprising a major amount of an oil of lubricating viscosity and a minor amount of a polyalkenyl sulfonate composition having a TBN of greater than 60 to about 400 wherein the polyalkenyl sulfonate is an alkali metal or alkaline earth metal salt of a polyalkenyl sulfonic acid derived from a mixture of polyalkenes comprising greater than 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers.